Each journal entry first appears during certain quests but if you progress through the quests without picking up the journals they will still appear. So if you waited until you finished Act II all six parts would appear at the same time.

Only one of your characters needs to find the journal for you to be credited with it.

To find out which journals you have found so far go to your Achievements list (press Y) and check:

Most commoners know Caldeum by reputation if not direct experience. The trade city has existed for thousands of years, predating even the Mage Clan Wars. Its neutral stance throughout the following centuries saved it from the destruction that visited the nearby city of Viz-jun and life - along with trade - carried on.

The trade consortium council has always been the ruling body of Caldeum, but it gained additional strength after the fall of the Vizjerei. The councilmen saw opportunity in the rapidly growing Zakarum faith, and they allowed the fanatics to build their enormous cathedral, Saldencal, within the center of the city.

Not content to reign supreme in commerce and religion, the trade consortium council aspired to make Caldeum a nexus of learning as well. It proposed to unite the mage academics in a massive new structure - the Yshari Sanctum - which has remained a beacon of knowledge and advancement ever since.

Caldeum changed drastically in recent years when the Kurast nobles all but invaded the city. Soon after, their emperor, Hakan I, joined them and made Caldeum his capital. Though his actions seemed audacious, he managed to bring further peace and prosperity to the city for the duration of his reign.

All was well under the new emperor until his untimely death forced the Zakarum priests to find a new heir for Kehjistan's throne. Through a series of elaborate rituals (undoubtedly a spectacle for their superstitious followers), they determined an impoverished infant in the north was Hakan I's spiritual successor.

After the Zakarum priests’' rituals were complete, they employed a group of reckless mercenaries, the Iron Wolves, to retrieve the child. They dubbed him Hakan II and installed him on the throne despite his scant years. Caldeum has been in decline ever since, and I can see no reprieve in sight.